Rename spatialomics to imaging for modules branch

[adamjtaylor]

As discussed on slack, @FloWuenne and @jmuhlich have proposed to rename the spatialomics directory in the modules branch to imaging. This better reflects the specific use cases for image registration, segmentation and quantification.

This will impact only two modules that are currently in development and will need to point towards this new directory

• New module Ilastik/pixelclassification modules#2875
• New module Ilastik/multicut modules#2894

[jmuhlich]

Will be closed by #821

[adamjtaylor]

Pending action:

Can you also open a quick PR that updates the tests/config/test_data.config file in the modules repo so we don't break any tests for modules dependent on the spatialomics data?